Validation of a novel system for co-registration of coronary angiographic and intravascular ultrasound imaging

INTRODUCTION: Intravascular ultrasound (IVUS) is a useful adjunct to guide percutaneous coronary intervention (PCI). Correlating IVUS images with angiographic findings can be challenging. We evaluated the utility of a novel co-registration system for IVUS and coronary angiography.
METHODS AND RESULTS: A 3-D virtual catheter trajectory was constructed from separate angiographic imaging runs using bespoke software. Intravascular ultrasound images were obtained using a commercially available mechanical rotational transducer with motorized pullback. Co-registration of ultrasound and angiographic images was then performed retrospectively based on the length of pullback, the 3-D trajectory and the start position of the catheter. Validation was performed in a spherical phantom model and in vivo in the coronary circulation of patients undergoing coronary angiography and intravascular imaging for clinical purposes. 111 paired angiographic and IVUS runs were performed in 3 phantom models. The differences between the reference length and the length measured on the 3D reconstructed path was -0.01 ± 0.40 mm. Intra-observer variability was 0.4%. We enrolled 25 patients in 3 European hospitals and performed 35 co-registration attempts with an 86% success rate. 71 landmarks were selected by the first operator, 68 by the second. Differences between angiographic and IVUS landmarks were -0.22 ± 0.72 mm and 0.05 ± 1.01 mm, respectively. Inter-observer variability was 0.23 ± 0.63 mm.
CONCLUSION: We present a novel method for the co-registration of IVUS and coronary angiographic images. This system performed well in a phantom model and using images obtained from the human coronary circulation.